Annealable layer system

ABSTRACT

A layer system that can be annealed comprises a transparent substrate, preferably a glass substrate, and a first layer sequence which is applied directly to the substrate or to one or more bottom layers that are deposited onto the substrate. The layer sequence includes a substrate-proximal blocking layer, a selective layer and a substrate-distal blocking layer. Also provided is a method for producing a layer system that can be annealed and has a sufficient quality even under critical climatic conditions and/or undefined conditions of the substrate. During the heat treatment (annealing, bending), the color location of the layer system is maintained substantially stable and the color location can be widely varied at a low emissivity of the layer system. For this purpose, a first dielectric intermediate layer is interposed between the substrate-proximal blocking layer and the selective layer and is configured as a substoichiometric gradient layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 11/575,985 filedon Sep. 18, 2007 which is a Section 371 filing of internationalapplication PCT/DE2005/001660, filed on Sep. 21, 2005 and published, inGerman, as international publication WO 2006/034676 on Apr. 6, 2006, andclaims priority of German Application No. 10 2004 047 135.5 filed onSep. 27, 2004, all of which applications are hereby incorporated byreference herein, in their entirety.

BACKGROUND ART

The invention relates to an annealable layer system with a transparentsubstrate, preferably a glass substrate, and a first layer sequencewhich is applied to the substrate directly or is applied to one of morebottom layers which are deposited on the substrate. The layer sequencecomprises a substrate-proximal blocking layer, a selective layer, and asubstrate-distal blocking layer.

The invention also relates to a method for producing an annealable layersystem, where in said method a first layer sequence is applied to atransparent substrate, preferably a glass substrate, either directly tothe substrate or to one of more bottom layers which are deposited on thesubstrate. The layer sequence therein comprises a substrate-proximalblocking layer, a selective layer, and a substrate-distal blockinglayer.

The customary blocking layers, which comprise silver layers(s) (forexample, an NiCr or NiCrOx layer, cf. patents DE 035 43 178 and EP 1 174379) or offer protection at least on one side, lead to a reduction ofthe conductivity of the silver layers(s). If a silver layer with aconductivity of ca. 5 ohm/sq. is deposited and this is embedded in twoNiCrOx layers, then this embedding can lead to an increase of theconductivity by ca. 1.5 ohm/sq. to 6.5 ohm/sq.

In EP 0 999 192 B1 a layer system is described which comprises a silverlayer as a selective layer which is provided on both sides with ablocking layer of nickel or nickel chromium. These blocking layersprotect the sensitive silver layer against being affected by neighboringlayers. Along with this, the layer system is stabilized during the heattreatment by inserting an NiCrOx layer into the functional silver layerwith a single low-E [coating]. The disadvantage consists in the factthat in this layer system each individual silver partial layer must beca. 7 to 8 nm thick in order to avoid the formation of islands of thesilver partial layers. This leads to a low transmission for the layersystem. Furthermore, in EP 0 999 192 B1 the use of a substoichiometricTiOx layer between the blocking layer and the silver layer is described,which is intended to reduce the formation of haze. This absorbing TiOxlayer oxidizes during the heat treatment, wherein significant changes oftransmission and a shift of the preset color location take place.

In this realization several layer sequences of sensitive silver layerswith bottom layers and each with two blocking layers enclosing therespective silver layer are also provided.

In practice, annealable layer systems are frequently required, i. e.layers which after application are subjected once again to a heattreatment, for example, in order to harden or bend them. The layerrepresented in EP 099 192 B1 [sic] does not exhibit such ability to beannealed since the blocking layers, as they are represented therein, arenot sufficiently resistant to diffusion processes so that, during theannealing, materials from neighboring layers can diffuse into the silverlayers, which leads to undesirable changes in color [so that] the colorlocation of the layer system cannot be kept stable.

In EP 1 238 950 A2 an annealable layer system is described whichprovides on both sides of a silver layer, as a sensitive layer, NiCrOxlayers as blocking layers. Furthermore, in this layer system, dielectricintermediate layers are provided which are located both above and belowthe blocking layers. Layers of this type also act as diffusion barrierduring the annealing processes.

Furthermore, in EP 1 238 950 the use of gradient layers in thestabilization of heat-treated layer systems is described. Thedisadvantage therein consists in the fact that the SiNx layer lies belowthe blocking layer, whereby the resistance, and thus the emissivity ofthe layer system, is not reduced.

It has been shown that layer constructs of this type are sensitive toclimatic conditions so that under demanding climatic conditions theselayer systems cannot be produced with a sufficient quality or yield.Also in the case of rough glass with undefined initial properties, thislayer system exhibits quality problems in manufacture.

BRIEF SUMMARY OF THE INVENTION

It is thus the objective of the invention to specify a layer system anda method for its production which ensure sufficient quality in case ofdemanding climatic conditions and/or undefined states in the glasssubstrate. It is furthermore the objective of the invention to enablecoating of a substrate with a layer system which can be heat-treated,where during the heat treatment (annealing, bending) the color locationof the layer system can be kept essentially stable and in case of lowemissivity of the layer system the color location can be varied widely.

In particular through a gradient structure of the dielectricintermediate layer the adhesive strength of the layer sequence can beimproved significantly so that in case of demanding climatic conditionsor in case of a substrate, preferably of rough glass with undefinedstarting conditions, which has led to adhesion problems in the layers,production methods can be controlled better. In this way the degradationof the silver layer during the heat treatment can also be prevented.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The invention will be explained in the following with the aid of threeembodiment examples. In the corresponding drawings are shown

FIG. 1 an annealable layer system with a silver (Ag) layer as selectivelayer and a dielectric intermediate layer,

FIG. 2 an annealable layer system with two Ag layers and a dielectricintermediate layer for each,

FIG. 3 an annealable layer system with two Ag layers and two dielectricintermediate layers for each, and

FIG. 4 a schematic representation of a part of a coating system forrealizing the layer system according to the invention.

As represented in FIG. 1, a glass substrate 1 is provided with a bottomlayer 2 of TiO2. Deposited thereon is a first blocking layer 3 ofNiCrOx. Since the bottom layer 2 already has properties of a blockinglayer, the first blocking layer 3 can also be omitted in given cases,which is marked by the use of parentheses.

Following this is a first dielectric intermediate layer 4. This firstdielectric intermediate layer 4 is deposited as a gradient layer, thatis, it passes, over the thickness of one stoichiometric layer ZnAlO,into a substoichiometric layer ZnAlOx. In so doing, the gradient fromZnAlO to ZnAZlOx is always directed in the direction of the following Aglayer as the first selective layer 5. This means that thesubstoichiometric part of the dielectric intermediate layer 4 is in thevicinity of the first selective layer 5.

The first selective layer 5 is subsequently provided with a secondblocking layer 6. Following that is a first closing layer 7 of SnO2 anda second closing layer 8 of Si3N4.

The production of the gradient layer takes place in such a manner thatwithin one coating compartment or within one recipient, through eitherof which the substrate is passed in one direction of movement, twomagnetrons, each with the same target material ZnAl, are disposed in thedirection of movement. First, the stoichiometric part of the firstdielectric partial layer 4 is deposited via the first magnetron lying inthe direction of transport. Thereafter, the substrate 1 runs through thearea below the second magnetron in which the substoichiometric part ofthe first dielectric intermediate layer is deposited by the secondmagnetron being operated at high power, while the same reactive gaspressure prevails in the pump compartment, whereby a substoichiometricratio develops in the part of the first dielectric intermediate layer 4.Since a greater sputter rate is also associated therewith, the secondmagnetron can be provided with a screen between the target and thesubstrate, said screen have a smaller opening than a screen between thetarget of the first magnetron and the substrate. Thus, the thicknessratios of the stoichiometric and substoichiometric partial layers can beset despite the different powers of the magnetrons, and thus thedifferent sputter rates.

Another possibility for production consists in the first magnetron beingdisposed in a separate recipient or the compartment being divided intotwo separate partial compartments and for each magnetron a separatereactive gas environment being provided. Thus, for the substoichiometricpart of the first dielectric intermediate layer 4, processing ispossible with lower reactive feed.

In FIG. 2 an annealable layer system is represented, in which, on thefirst layer sequence 9 (comprising a first blocking layer 3, a firstdielectric intermediate layer 4, a first selective layer 5, a secondblocking layer 6, and a first closing layer 7), a second layer sequence10 is disposed with a second selective layer 14, a third blocking layer12, and a third dielectric layer 11 [sic].

Described in FIG. 3 is an annealable layer system which is similar tothe layer system in FIG. 2, but with the difference that between thefirst selective layer 5 and the second blocking layer a seconddielectric intermediate layer 13 [sic] [is disposed] and between thesecond selective layer 14 and the fourth blocking layer 15 a fourthdielectric layer 16 [is disposed].

In FIG. 4 a part of a coating system is represented in schematic form,said coating system serving for building up a layer system according tothe invention.

In this coating system the substrates 1 can be moved through theindividual coating stations in a transport device 17, where a separationof the individual stations is realized by flow resistors 18 or gas locks19 with flow resistors 18.

A two-stage ion beam station 20 is followed, after a flow resistor 18,by a TiOx coating station 21. Following this, after a flow resistor 18,is a first NiCrOx coating station 22 [sic]. Following an additional flowresistor 18 is a first coating compartment 23 with two magnetrons 24which are operated at different powers, the left magnetron 24 at lowerpower than the right. Thus, a dielectric intermediate layer 4 or 11 isdeposited, where the substoichiometric part of the first dielectricintermediate layer 4 or 11 abuts the Ag layer 5 or 14, which isdeposited in an Ag coating station 25 following after a flow resistor18. For generating an additional dielectric intermediate layer 13 or 16a second coating compartment 26 follows, where there the left magnetron27 runs at higher power than the right, otherwise, however, the secondcoating compartment 26 has a structure analogous to the first 23.

The second coating compartment 26 is followed, after a flow resistor 18,by a second NiCroX coating station 28. Up to this point, due to thelayer structure, all the stations could be separated via flow resistors18. Only a subsequent Sn coating station 29 is separated via two gaslocks 30, which in turn are flanked on both sides by flow resistors 18.

This is followed by a Si:Al coating station 31.

1. Annealable layer system comprising a transparent substrate, and afirst layer sequence which is applied to the substrate directly or toone or more bottom layers which are deposited on the substrate, whereinthe layer sequence comprises a substrate-proximal blocking layer, afirst selective layer, and a substrate-distal blocking layer, and afirst dielectric intermediate layer is disposed between thesubstrate-proximal blocking layer and the first selective layer, and thefirst dielectric intermediate layer comprise a nitride layer whichwithin a thickness of the nitride layer is at least partiallysubstoichiometric.
 2. Annealable layer system according to claim 1,wherein the nitride layer comprises SiNx or AlNx.
 3. Annealable layersystem according to claim 1, wherein the first intermediate layercomprises a gradient layer with a gradient that passes from astoichiometric part to a substoichiometric part, and where the gradientpoints in a direction of the first selective layer, such that thesubstoichiometric part of the gradient layer lies on a side of the firstselective layer.
 4. Annealable layer system according to claim 1,wherein nitrogen content decreases in direction of the first selectivelayer.
 5. Annealable layer system according to 1, wherein the layersequence comprises a TiO2 layer, the substrate-proximal blocking layer,a gradient layer, the first selective layer, the substrate-distalblocking layer, an SnO2 layer, and an Si3N4 layer.
 6. Annealable layersystem according to claim 1, further comprising, between the firstselective layer and the substrate-distal blocking layer, a seconddielectric intermediate layer.
 7. Annealable layer system according toclaim 1, further comprising a second layer sequence disposed on thefirst layer sequence, directly or with additional layers lyingtherebetween.
 8. Annealable layer system according to claim 1, whereinthe transparent substrate comprises a glass substrate.